DESCRIPTION

The first report produced gives averages since the last reboot. Additional
reports give information on a sampling period of length delay.
The process and memory reports are instantaneous in either case.

Options

The -a switch displays active/inactive memory, given a 2.5.41 kernel or better.

The -f switch displays the number of forks since boot.
This includes the fork, vfork, and clone system calls, and is
equivalent to the total number of tasks created. Each process
is represented by one or more tasks, depending on thread usage.
This display does not repeat.

The -m displays slabinfo.

The -n switch causes the header to be displayed only once rather than periodically.

The -s switch displays a table of various event counters
and memory statistics. This display does not repeat.

delay
is the delay between updates in seconds. If no delay is specified,
only one report is printed with the average values since boot.

count
is the number of updates. If no count is specified and delay is
defined, count defaults to infinity.

The -d reports disk statistics (2.5.70 or above required)

The -D reports some summary statistics about disk activity.

The -p followed by some partition name for detailed statistics (2.5.70 or above required)

The -S followed by k or K or m or M switches outputs between 1000, 1024, 1000000, or 1048576 bytes

The -V switch results in displaying version information.

FIELD DESCRIPTION FOR VM MODE

Procs

r: The number of processes waiting for run time.
b: The number of processes in uninterruptible sleep.

Memory

swpd: the amount of virtual memory used.
free: the amount of idle memory.
buff: the amount of memory used as buffers.
cache: the amount of memory used as cache.
inact: the amount of inactive memory. (-a option)
active: the amount of active memory. (-a option)

Writes

IO

cur: I/O in progress
s: seconds spent for I/O

FIELD DESCRIPTION FOR DISK PARTITION MODE

reads: Total number of reads issued to this partition
read sectors: Total read sectors for partition
writes : Total number of writes issued to this partition
requested writes: Total number of write requests made for partition

FIELD DESCRIPTION FOR SLAB MODE

cache: Cache name
num: Number of currently active objects
total: Total number of available objects
size: Size of each object
pages: Number of pages with at least one active object

NOTES

vmstat
does not require special permissions.

These reports are intended to help identify system bottlenecks. Linux
vmstat
does not count itself as a running process.

All linux blocks are currently 1024 bytes. Old kernels may report
blocks as 512 bytes, 2048 bytes, or 4096 bytes.